In a molten carbonate fuel cell, after a fuel gas such as natural gas has been humidified by steam, the resulting gas is allowed to react with a modifying catalyst, and then supplied to a fuel cell. In this case, conventionally, the humidifying process is carried out by mixing the fuel gas at normal temperature and steam generated by a boiler in a unit separated from the boiler.
In the conventional humidifying process of this type, two units, that is, the boiler and a mixing device, are required, inevitably resulting in a large-size facility. In order to solve this problem, there have been strong demands for a gas humidifier that is developed so as to carry out a steam-generating process and a process for mixing the generated steam and the fuel gas by using a single unit.
The objective of the present invention is to provide a small-size gas humidifier which can effectively execute the steam-generating process and the humidifying process by the generated steam and the fuel gas by using a single unit.